Cooling fan



FAN

L L E w D L A G F.

COOLING Filed Nov. 3, 1921 1930. F. W. CALDWELL COOLING FAN Filed Nov.3, 1921 2 Sheets-Sheet 2 H074 TIONAL I VELOCITY All? 1 /7555 U/PEHUMTIUNAL VEL OC/TK 5] wuento'c Patented May 6, IQSO I UNITED STATESPATENT; OFFICE FRANK W. CALDWELL, OF DAYTON, OHIO COOLING FANApplication filed November 3, 1921. Serial 1T0. 512,408.

This invention relates to fans and more views illustrating the action ofcentrifugal particularly to a cooling fan for an autoforce on the blade.mobile engine. In these drawings I have illustrated one The greatestneed for the cooling fan for embodiment of my invention and have 5 anautomobile engine occurs when the autoshown the same as comprising a fanin which 50 mobile is moving at a relatively slow speed each of theblades is mounted for movement with the'engine'under aheavy load, aswhen about an axis extending lengthwise of the the car is climbing ahillon high gear, Whe blade. The movement of the blades about the automobileis runnin atarelatively high ir respe tive longitudinal axes is conspeedenough air flows t rough the radiator, trolled by a suitable yieldingdevice which 55 as a result of the speed of the automobile, wlllretainthem in their normal, or operato provide ufli i nt o li f th i tive,positions until the engine has reached Inasmuch as th f b b a great d la predetermined speed and which will then of power it is desirable thatit should be so Permit them to rotate about Said longitudinal controlleda to Save thi power h th f axes into ppsitions which will so alter the60 is-not needed for c li pm-P0ses 7 blade angles as to cause the sameto operate One object of th i ti i t id a as a w1nd mill. It Wlll beunderstood that fan of such a, character th t, h th t the articularembodiment here illustrated mobile is moving at such a speed that thefan h n Chosen t Pl p of mustm' i t i d f li purposes it ill tron onlyand that the fan itself may take va- 65 absorb littl no power f th irlous forms and the detallsof constructlon It is a further object of theinvention to may be wldely flamed from these hereshewnprovide suchafanin which the blade angles In thetipel'tleuler tern? of the devlee hereof the fan will be automatically-altered, when Illustrated the fancemPmseS P' the automobile reaches a certain predeter- P g Struetllre,Whleh 15 1 70 mined speed, to cause the fan to operate as a Dated In a eg 23nd may be epemtlvely .wind mill, so that no engine power isreconnected Wlth asource of POYV Such as an qui d t Operate inautomobile eng ne, in any suitable manner.

A further object of the invention is to pro .'Mounted on thls hub aremore ten vide a fan of this kind which will be simple the P n havmgfour, and in its construction and operation and which e Q these bladesrotatable atflmlt may be easily maintained in an operative axle extendmgtengthwflse 'e re thls diti end each blade is provided at its inner endOther objects of the invention will appea with trunnion which isleul'neled in a as the device is described in detail. suitable bearingin the supporting structure, 0

In the accompanying drawings Fig. 1 is an hub, AS here h the PP e" endview of a fan embodying my invention; Structure 15 hollow, P p and tFig. 2 is a sectional-view taken centrally tl'lmmons extent; q g t e f'through the hub of such a fan; Fig. 3 is a and are e 1n posltwn 1nbearmss 40 transverse section taken on the line 33 of y cellars 5 g e ySecured t t ends 85 Fi 2; Fi 41 a did ti l i h thereof If desired,antlfrlctlon bearings 6 ing a section of a fan blade in its normal y bemterposed between the e e and the iti Fi 5 1 a imi w Showing h hubstructure to reduce the frictional consection'of the fan blade initsreverse positact between these P 45 tion; and Figs. 6 and 7 are.diagrammatical Smteble means are Prevlded for heldmg 'ture. This stud isarranged centrally of the supporting structure and has rotatably'mounted thereon a sleeve 8 having at its outer end a circumferentialfiange9 which are provided a plurality of recesses 10, there being onesuch recess for each blade. The inner end of the sleeve is recessed, asshown at 11, and the end walls of this recess serve as stops whichcooperate with a fixed stop, or lug, 12, carried by the end wall of thehub structure and extending intothe recess. Each fan blade is connectedwith the sleeve so that the rotation of the fan blades about theirlongitudinal axes will impart-rotatory movement to the sleeve. As hereshown, the

collar 5 of each bla'dehas rigidly secured thereto an arm 13, the outerend of which extends into the corresponding recess 10 in the flange ofthe sleeve. Preferably the outer ends of the arms 13 are spherical toreduce the frictional contact between the same and walls of therecesses. The ieeve,

and consequently, the'blades-are held normally against rotatory movementby means of a spring 14 which is coiled about the outer end portion ofthe stud, or shaft, 7 and has one end secured to the sleeve and theother and secured to a collar 15 which is rigidlysecured to the stud, orshaft, 7. I The tension of the spring may be regulated by adjusting thecollar 15 on the stud 7 and to this end the collar is screw threadedonto the stud and then secured against rotation by means of a pin 16.

In the present construction centrifugal force is utilized to rotate thefan blades about their longitudinal-axes andthus alter the blade angles.The action of the centrifugal force on the blade may be explained byreference to Figs. 4: and 7. Fig. 4 shows the air force acting on asection of an ordinary fan blade and it will be apparent that the airpressure on the blade is such as to resist the revolution of the fan. InFig. 5' the angle between the blade section of the fan and the plane ofrevolution has been reduced to such an extent that the air pressure willbe substantially. reversed and will cause the fan tofunction as a windmill. With the blade in the position shown inFig. 5 it will be apparent,therefore, that the air flowing through the radiator of an automobilemoving at high speed will assist the revolution of the fan to such anextent that little or no power will be requiredto operate the same.

As has been stated, centrifugal force is utilized to so alter the bladeangles and in Fig. 6 I have shown a plan view of a typical fan bladewhich may be considered as dimay be taken as equal to D-F, and will havea component D-B which is perpendicular to the center line of the blade.

If these components are now transferred to the sectional view in Fig. 7it will be obvious that they act upon the respective portions of theblade in opposite directions and thus tend to produce a twistingmovement which will reduce the angle between the blade section and theplane of revolution. This twisting movement is produced by thecentrifugal force and is proportional to the square of the revolutions.Obviously as the speed of the engine increases the centrifugal force onthe fan blades will increase until when the automobile reachesa speed-atwhich the fan is no longer necessary for cooling purposes the twistingaction of the centrifugal force on the blades will be suflicient toovercome the tension of the springlet, thus permitting the blades tomove from the position shown in Fig. 4 to the position shown in Fig. 5and converting the fan into a wind mill which will be operated by theflow of air through the radiator, thereby greatly reducing, or entirelyeliminating, the absorption of power" by the fan from the engine. Whenthe blades have moved to the desired position their further rotation isprevented by the stop 12, and as the speed of the engine falls theblades will be returned to their normal positions by the action of thespring 14', the movement in this direction also being limited by thestop 12.

While I have shown and described one embodiment of my invention I wishit to be understood that I do not desire to be limited to the detailsthereof as various modifications may occur to a person skilled in theart.

Having now fully described my invention what I claim as new and desireto secure by Letters Patent, is: V 1. In a fan, arotatable supportingstructure, a blade mounted on said structure for movement by the actionof centrifugal force thereon about an axis extending lengthwise of saidblade and held against longitudinal. movement, a member rotatable withrelation to said supporting structure about an axis extendingtransversely to said axis of said blade, an operative connection betweensaid blade and said member, and a spring acting on said member to resistits rotation by said blade.

2. In a fan, a rotatable supporting structure, a blade mounted on saidstructure for movement by centrifugal force about an axis extendinglengthwise of said blade, a stud carried by said supporting structure, amember rotatably mounted on said stud, an operative connection betweensaid member and said blade, and a spring coiled about said stud andconnected at one end with said memher and at the other end with saidstud.

3. In a fan, a rotatable supporting structure, a blade mounted on saidstructure for movement by centrifugal force about an axis extendinglengthwise of said blade, a stud rigidly secured to said supportingstructure, and extending transversely to the axis of said blade, a partrotatably mounted on said stud and having a recess therein, an armextending radially from said blade and having one end arranged in saidrecess, and a spring coiled about said stud and connected at one endwith said part and at theother end I with said stud.

4. In a fan, a rotatable supporting structure, a blade mounted on saidstructure for movement b centrifugal force about an axis extendinglengthwise of said blade, a stud rigidly secured to said supportinstructure, and extending transversely to t e axis of said blade, a partrotatably mounted on said stud and having a recess therein, an

arm extending radially from said blade and having one end arranged insaid recess, and a spring coiled about said stud and connected at oneend with said part and at the other end with said stud, and a stop forlimiting the movement of said part.

5. In a fan, a hollow supporting structure having an axial stud rigidlysecured thereto, a plurality of fan blades mounted on said supportingstructure for movement about axes extending lengthwise of the respectiveblades, a sleeve rotatably mounted on said stud and having at one end aflange rovided with recesses, an arm rigidly secure to each blade andhaving its end extending into one of said recesses, a stop to limit therotation of said sleeve, and a spring coiled about said stud and havingone end connected with said sleedve and the other end connected withsaid stu 6. In a fan, a rotatable supporting structure, a blade mountedon said structure for movement about an axis extending lengthwise ofsaid blade, a stud carried b said supporting structure, a member rotataly mounted on said stud, an operative connection between said member andsaid blade, and a spring acting on said member to resist its rotation bysaid blade.

7 L In a fan, a rotatable supporting structure, a blade mounted'on saidstructure for movement about an axis extending lengthwise of said blade,a stud rigidl secured to said supporting structure an extendingtransversely to the axis of said blade, a part rotatably mounted on saidstud and having a recess therein, an arm extending radially from saidblade and having one end arranged in said recess, and a spring coiledabout said stud and connected at one end with said part and at the otherend with said stud.

8. In a cooling fan for an automobile engine, a fan blade mounted forbodily movement'about an axis extending transversely thereto and formovement about a longitudinal axis located between the lateral edgesthereof and in such relation to the mass of said blade that the movementof said blade about said transverse axiswill cause it to move about saidlongitudinal axis in a direction to decrease the angle thereof as thespeed of movement about said transverse axis increases, and means torestore said blade to its initial position with relation to saidlongitudinal axis.

9. In a cooling fan for an automobile engine, a fan blade mounted forbodily movement about an axis extending transversely thereto and formovement about a longitudi-' longitudinal axis until the movement aboutsaid transverse axis reaches a predetermined speed.

10. In a cooling fan for an automobile engine, a fan blade held againstlongitudinal movement and mounted for bodily movement about a transverseaxis and for movement about a longitudinal axis located between thelateral edges thereof and in such relation to the mass thereof that theaction on said blade of centrifugal force resulting from the move mentthereof about said transverse axis will cause said blade to move aboutsaid longitudinal axis in a direction to decrease the angle thereof asthe speed of movement about said transverse axis increases, andyieldable means to resist the movement of said blade about saidlongitudinal axis.

11. In a cooling fan for an automobile engine, a fan blade held againstlongitudinal movement and mounted for bodily movement about a transverseaxis, and for movement by the action of centrifugal force thereon abouta longitudinal axis in a direction to decrease the angle thereof as thespeed of movement about said transverse axis increases, and means tocontrol the movement of said blade about said longitudinal axis.

12. In a cooling fan for an automobile enine, a rotatable supportingstructure,.a fan filade mounted on said structure for movement withrelation thereto, by the action of centrifugal force on said blade,about a longi- 5 tudinalaxis in adirection to decrease the angle thereofas the speed of rotation of said supporting structure increases, andmeans for holding said blade against movement about said longitudinalaxis until said supporting structure is rotated at a predeterminedspeed. In testimony whereof, I aflix my signature hereto.

' FRANK W. CALDWELL.

